A. Field of the Invention
The present invention relates to a plastic forming apparatus for making a plastic panel with transverse ribs. More particularly, the present invention relates to a manufacturing apparatus for making a plastic panel with rib folds such as a root barrier panel material used in the landscaping field to control outgrowth of tree roots.
B. Description of the Prior Art
Folding machines for sheet plastic or sheet metal or the like are plenty. A more advanced type of such an apparatus is disclosed in U.S. Pat. No. 6,939,284 to Trovinger at al. the disclosure of which is incorporated herein by reference. Trovinger teaches a sheet folding apparatus with a rounded fold blade. Trovinger's patent makes a single center fold of a piece of sheet using a fold roller that runs around a round fold blade and depresses the sheet material between the fold blade. When regularly distanced transverse folds are necessary on a continuous supply of plastic sheet for use in various constructive walls that need ribs, this and other known devices come short in providing an adequate speed and quality of evenly spaced ribbed sheets or plates.
An object of the present invention is to provide an automatic rib forming apparatus for thermoplastic sheet plastic that is mechanically simplified and optimized to produce a speedy folding of well-defined ribs from a flat surface.
Another object of the present invention is to provide a novel combination of rack-and-pinion gears with four-bar linkage of parallel motion to mold and advance the sheet material to optimize the otherwise complex machine operations.
Yet another object of the present invention is to provide a method of forming an elongated panel with transverse ribs with improved efficiency.